Fluid handling systems are often used in handling corrosive materials or products that must be maintained in a high state of purity. One type of fluid handling system includes bulk fluid transport tankers. Fluid tankers and associated piping and valve components are typically made of stainless steel or other corrosion resistant metallic material. Some tanks are passivated at predetermined time intervals to maintain a protective coat on the tank interior to help increase corrosion resistance. However, tankers are often used to carry acids and corrosive chemicals that will attack virtually any type of metal over a period of time. Examples of such fluids include hydrochloric acid, hydrofluoric acid, ferric chloride, and bleach, to name a few. Transport of these chemicals requires that the tank surfaces and associated components are protected from adverse effects of contact with the cargo by a lining material. Typical tank lining materials are natural rubber, chlorobutyl, or hypalon. The associated piping and valves have also been lined.
Efforts have been made to develop a lined valve to use with such applications. These prior art lined valves typically have a lining permanently affixed (i.e. bonded, molded) to the interior of the valve. This creates a problem if the lining of the permanently lined valve is damaged, as the entire valve will need to be replaced.
Another problem is that the tank and tank valves must be cleaned periodically, especially when the tank will be used to transport a different chemical. The new chemical may react with the previously transported chemical which may not have been completely removed from the tank or valve components. The prior art permanently lined valves are difficult to clean within the confines of the valve.
The lining material typically used in prior art valves are relatively soft and somewhat flexible. The valves are typically designed so that the various lining pieces seal against each other. This can lead to cold flow and eventual leaking of the valve.
Another limitation of prior art valves involves the flow blocking device (butterfly disc, diaphragm, rotary plug, or ball), which is also typically coated with a permanently affixed lining material. If the lining on the flow blocking device is damaged, the entire valve needs to be replaced. Also, the permanent coating increases the thickness of the flow blocking device thereby reducing the volume of fluid flow.
Accordingly, there is need for providing an improved lined valve over current known valves that overcomes one or more of these problems.